A number of patents have issued in recent years regarding the puffing or expansion of tobacco products. For example, U.S. Pat. Nos. 3,409,022 and 3,566,112 describe such processes. Other patents have also issued in this area. Each of the patents relates to a method of puffing or expanding the tobacco.
Tobacco is a fibrous, botanical product and the expansion obviously involves an increase in the area and spacing between the fibers. For this reason, expansion weakens the fibrous structure which normally comprises the tobacco part. Because of the weakness which is thus introduced, in some cases the tobacco part incorporated in a smoking product may not retain the size to which it was originally expanded. If the tabacco particle collapses, then the benefits of the expansion are totally or partially lost.